1. Field of the Invention
The present invention, in general, relates to battery chargers and, more particularly, to the charging and restoration of storage batteries.
Battery chargers are well known devices used for automotive, commercial, marine, aviation, and military applications to restore an electrical charge to a dead or weak battery.
While batteries are used for many purposes, there are three general categories in which they are most often used. The three categories include applications in which the battery (or group of batteries) are used for engine starting, lighting and ignition (hereinafter referred to as “SLI”) applications.
Lead-acid storage batteries are the most common of these types of batteries and it is a 12-volt lead acid type of battery that is described herein for use with the instant invention. However, the instant invention is applicable for use with any type and voltage of a battery that can benefit from the improvements herein provided.
With many applications, such as automotive, a battery is typically held near or at its maximum charge capacity by the charging system of the vehicle. When power is drawn from the battery, for example to start the vehicle, it is soon replenished by the vehicle's charging system. This is an ideal operating environment for a battery and maximum battery life-expectancy is usually realized.
However, there are many situations in which a battery is not used for a protracted period of time, or if used, is not recharged. This is especially hard on lead acid types of batteries.
In some cases the batteries are initially charged to capacity but are then left for weeks or months without being used or serviced. The battery naturally loses its charge (i.e., its reserve and starting capacity) by self-discharge from the local action of impurities of the lead plates and interaction with the electrolyte.
This self-discharge is accelerated at elevated temperatures, and will eventually result in a drop in the terminal voltage of the battery, especially below 1.75 volts per cell (10.5V total for a 12V battery).
Once this threshold is reached, and the battery is left for as little as 24 hours without recharge, it results in lead sulfate particles crystallizing on surfaces of the positive and negative plates. These lead sulfate crystals form a high electrical-resistance that is difficult to remove from the battery plates. This tendency is generally well known and is also discussed in U.S. Navy T.O. 8DZ-62-1. The term “sulfate” or a derivative thereof refers to this action.
This crystallized lead sulfate coating substantially increases the internal impedance of the battery. This, in turn, prevents normal battery function from occurring. The battery is no longer capable of delivering sufficient power to a load. Similarly, the high internal impedance affects the ability of the battery to be re-charged.
When a battery charger is connected to a “sulfated” (as it is sometimes referred to in the industry) type of battery, the high internal impedance prohibits re-charging of the battery. The battery charger can remain connected for hours, even days or weeks to no avail. The battery simply will not accept charge current.
In some cases the sulfated battery may gradually begin to accept a charge and be restored but in the vast majority of cases a conventional type of prior art battery charger cannot penetrate the high-impedance sulfated layering that has been deposited on the lead plates of the battery sufficient to dislodge the sulfurous materials or compounds (which are derived from the sulfuric acid) and restore them once again properly back into the electrolyte which includes sulfuric acid. Prior art battery chargers which are used to desulfate are sometimes effective only after very long periods of time after connection. This can often be weeks.
The result is that virtually all sulfated batteries presently are discarded and environmentally hazardous unless properly recycled. Sulfated batteries that have been in vehicles that have not been used or in storage have experienced little or no use are then regarded as useless and are discarded (or recycled). This causes a tremendous waste of resources as well as an enormous financial cost.
The cost to replace a sulfated battery is far more than the mere cost of a replacement battery. The cost of transportation including the time and labor necessary to transport and discard the sulfated battery, the payment of any recycling fees associated therewith, and the cost of transportion, including the time and labor necessary to obtain a replacement battery, add considerably to the cost as does the labor associated with the removal of the old battery and the installation of the new one. Sometimes, the total cost to replace a sulfated battery may be a multiple of the cost of the replacement battery, alone.
There are other causes that contribute to the formation of lead sulfate crystals. Another common cause contributing to the rapid formation of the crystallized lead sulfate coating is by storing a highly discharged battery for even a relatively short period of time, such as 3-4 days, without recharge when an electrical load is also connected to the battery. This is a common problem when lights or other loads are left on batteries for protracted periods of time.
As with self-discharge, high temperatures can further accelerate the sulfating problem. In either case the high resistance crystallized lead sulfate coating eventually results in a “dead” battery with high internal impedance that can not typically be recharged. The sulfated battery may still present some voltage at the battery terminals, but because of the high internal resistance it cannot supply anywhere near a normal current draw, and is therefore considered as dead regardless of whether there is any voltage present at the terminals.
Also, in some cases a conventional type of a battery charger requires a minimum voltage to be present at the battery terminals in order for the charger to even begin to set-up to deliver a charging current to the battery. This may be to ensure that the charger is properly connected to the “right” type of battery, etc., prior to commencing a charge cycle.
Battery chargers are increasingly becoming more sophisticated in operation and these types of operating safeguards are being incorporated into many types of battery chargers to ensure safe operation. Batteries contain a great deal of energy. They can emit hydrogen gas, which is explosive. Accordingly, the safe charging of batteries is potentially of life and death criticality.
A dead sulfated battery may present a terminal voltage that is equal to or close to zero volts. Accordingly, certain prior art types of battery chargers will not even attempt to deliver a charging current to such a battery.
In other cases, the terminal voltage of the battery may range from about one and one-half volts DC to a high of about eight or at most nine volts DC for a partially discharged sulfated type of battery. Even this range may present too low a terminal voltage to permit many types of prior art battery chargers from functioning.
Even if a standard type of a battery charger will set-up and attempt to deliver a charging current, the battery's high internal impedance (electrical resistance) will prevent a sufficient charge current from flowing into and through the battery.
The charger may remain connected, as mentioned above, to the battery for days without charging the battery, with current flows in the microampere or low milliampere rate.
Sometimes when this occurs, the battery may eventually begin to receive charge by gradually “ramping-up” the rate of charge as the lead sulfate crystals gradually break down sufficient to lower the battery's internal impedance. However, this could take days and sometimes weeks to occur. A protracted charging period wastes both energy and manpower.
However patient a person may be, usually there is never any substantial decrease in internal resistance of the sulfated battery, regardless of how long a conventional type of battery charger is connected. Because the internal impedance remains high, the battery is never able to accept a sufficient charging current. Accordingly, these types of batteries must presently be scrapped.
These general types of battery problems are universal worldwide in transportation, industry, passenger vehicles, military and elsewhere.
Any attempt to rejuvenate a dead or a sulfated battery is often referred to as either “restoring” or “conditioning” the battery. As used herein the terms, “conditioner”, “condition”, and “conditioning” are intended to include any restoring or rejuvenating activity or similar effort that is intended to add an electrical charge or otherwise improve the performance of a sulfated or discharged battery.
Similarly the terms, “sulfate”, “sulfated, “sulfating,” etc. as used herein, are intended to refer to a lead acid type of battery and the occurrence of sulfate crystals anywhere on the lead plates of the battery.
Accordingly, there exists today a need for battery conditioner and charger that can help ameliorate the above-mentioned problems and difficulties.
Clearly, such an apparatus would be a useful and desirable device as would a method to rejuvenate a sulfated battery.
2. Description of Prior Art
Battery chargers are, in general, known. While the structural arrangements of the above described known devices may, at first appearance, have similarities with the present invention, they differ in material respects. These differences, which will be described in more detail hereinafter, are essential for the effective use of the invention and which admit of the advantages that are not available with the prior devices.